Index: tests/utf8filter.cpp
--- tests/utf8filter.cpp.orig
+++ tests/utf8filter.cpp
@@ -1,6 +1,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <memory>
+#include <unistd.h>
 #include <libHX/io.h>
 #include <gromox/defs.h>
 #include <gromox/util.hpp>
